Quantitative Proteomics of Milk Whey Reveals Breed and Season Specific Variation in Protein Abundance in Holstein Friesian Cow and Murrah Buffalo

Bovine milk contains different components with nutritional and immunological benefits. It is easily accessible and a rich source of potential markers reflective of pathophysiological conditions; however, little is known about the changes in protein abundance associated with variation across breeds and seasons. In this study, we performed a comprehensive proteomic profiling of whey proteins from Holstein Friesian cow and Murrah buffalo across summer and winter seasons. Collectively, 490 proteins were identified with 113 and 144 differentially expressed proteins across seasons in cow and buffalo, respectively. Breed specific proteins like secretoglobin, e-cadherin and cathepsin-L were detected exclusively in HF, while basigin, conglutinin, and thrombomodulin were identified exclusively in Mu. Acute phase proteins (e.g. haptoglobin and α1AG) were more abundant in summer while antimicrobial proteins (e.g. conglutinin and osteopontin) were upregulated in winter. Similarly, proteins involved in lipid homeostasis (e.g. perilipin 2 and acyl CoA binding protein) showed breed specific variations. Selected representative mass spectrometric proteins (e.g. gelsolin and osteopontin) were validated by Western blot analysis. Results of this study indicate the dynamic nature of milk protein and provide a foundation for future studies of whey proteins which may be linked to diseases specific across breeds and seasons.